Treatment of keratinous substrates

ABSTRACT

A process for the modification of monomer pretreated keratinous substrates which comprises treating said substrate with a small but effective amount of a copper ammonium hydroxide solution.

United States Patent Giuseppe Anzulno Vercelll. Italy;

Clarence Ralph Robbins, Piscataway, NJ. 2,944

Jan. 14, 1970 Nov. 9, 1971 Colgate-Palmolive Company New York. N.Y.

Inventors Appl. No. Filed Patented Assignee TREATMENT OF KERATINOUS SUBSTRATES l 1 Claims, No Drawings US. Cl 8/1275, 8/127.51. 8/128 Int. Cl 006m 3/00, D06m 3/02, D06m 13/00 Field of Search 8/1275.

Primary Examiner-George F. Lesmes Arr/slam Examiner-B. Bettis murmurs-Herbert S. Sylvester. Murray M. Grill, Norman Blumenkopf. Ronald S. Cornell. Robert A. Burroughs Thomas .1 Corum, Richard N. Miller and Robert L, Stone ABSTRACT: A process for the modification of monomer pretreated keratinous substrates which comprises treating said substrate with a small but effective amount of a copper ammonium hydroxide solution.

TREATMENT OF KERATINOUS SUBSTRATES The present invention relates, in general, to the treatment of keratinous substrates and in particular to the provision of novel means for synergistically enhancing the physical properties of a wide variety of keratinous substances such as typified by human hair, animal hair, wool and the like.

As is well known, keratinous substrates may be modified physically and/or chemically by suitable processing. Thus, the treatment of human hair for purposes of permanent waving as well as other conditioning constitutes well-established technology, the relevant techniques being described in the published literature, both patent and otherwise. Thus, with reference to the treatment of human hair for purposes of imparting curl thereto, conventional processing involves a multistep procedure, the initial operation comprising solution impregnation of the hair fibers with a suitable reducing medium, the reducing solution treatment serving to effect substantial reduction of the keratin material whereby to convert cystine linkages i.e., disulfide bonds to mercaptan. The desired modification of the fiber material is subsequently effected by treating the keratin mass with a suitable oxidizing solution in known manner. The processing solutions and materials required for the implementation of such techniques are likewise well known in the art, being available commercially in a wide variety of forms. Although keratin-modification methods of the aforedescribed type are exploited to a significant extent on a commercial scale, such methods have nevertheless been found in practice to be subject to one or more disadvantages which tend to detract considerably from their commercial desirability. Perhaps, the primary objection concerns the failure of such processing to provide a final hair set possessed of the requisite form-retention stability, the latter condition being essential as regards any possibility of attaining satisfactory hair flexibility and structural integrity devoid of undesired brittleness, hardness, etc. Other disadvantages found to characterize keratin-modification methodology heretofore provided include, for example, the objectionable tendency to yield a hair product of inferior body, thickness, lustre etc. in practice, it has also been determined that many of the compositions incident to such processing e.g., permanent wave compositions, wave sets and the like, characteristically yield undesired film deposits which exhibit a highly objectionable tendency to flake off, dry to a hard friable deposit and/or discolor the hair as well as other physical impairment.

Nevertheless, the failure of the keratin-modification treatments heretofore described to provide a final hair set of optimum structural integrity i.e., in terms of elasticity, tensible strength, form retention capacity, flexibility, resilience and the like has proved of paramount importance and continues to challenge the relevant technology.

As a result of the foregoing situation, considerable industrial activity has centered around the research and development of methods and compositions specifically and beneficially adapted for use in connection with techniques devised to enable purposive, predetermined modifications in the properties of keratinous substrates absent detrimental effects upon the strength characteristic of the fiber selected for treatment.

Thus, in copending application, Ser. No. 829,097 there is described a multistep procedure for the treatment of keratinous materials whereby to achieve selective modifications in one or more properties, the involved process comprising the sequential steps of l. reduction 2. rinsing 3. oxidation in accordance with such processing, initial reduction of the keratin material is effected by treating same with a reducing solution for a time sufficient to permit substantial reduction of the keratin substrate, the term reduction" here connoting the conversion of cystine linkages i.e., disulfide bonds to mercaptan. Upon completion of the desired extent of reduction, the keratin material is subjected to a thoroughgoing rinsing operation for purposes of completely removing residual reducing agent. Intermediate rinsing comprises a particularly critical phase of the overall processing scheme, the improvements and advantages described depending pivotally thereupon. Upon completion of the rinsing step, the keratin material is subjected to oxidation with a solution comprising vinyl-type monomer in the presence of free radical-liberating catalyst whereby to attach polymerized monomer segments to the individual keratin fibers.

Another technique for effecting the modification of keratinous substrates is described in copending application, Ser. No. 829,095, the salient characteristic of this particular method residing in the use of a highly specific catalyst material, namely persulfuric acid and/or its water-soluble salts. The use of this specific catalyst material obviates any necessity for the use of multistep processing while permitting realization of the desired degree of keratin modification. Thus, the contemplated objectives are achieved by the use of a single processing solution containing as essential ingredients the monomer material and persulfuric acid catalyst.

Yet, another technique for effectively modifying the properties of keratinous substances is that described in copending application, Ser. No. 829,096. This particular method entails the significant advantage that polymer grafting can be synergistically enhanced or otherwise augmented by effectuating the monomer-treating operation in the presence of small but effective amounts of a water-soluble halide salt i.e., a salt of bromine with a water-solubilizing cation such as lithium, sodium, potassium, ammonium, substituted ammonium and the like. According to such processing, significant improvement in polymer takeup rate is attainable in the absence of adverse effects upon other properties considered desirable if not necessary in the keratin material.

Dissimilar but nevertheless somewhat analogous keratin treatment methodology is likewise described in the published literature both patent and otherwise. In the main, such processing involves as an essential expedient the treatment of wool or similar fabric with a reducing agent, such impregnation treatment being designed to deposit upon and within the fibers effective quantities of such reducing agent e.g., ferrous sulfate.

In any event, and regardless of the particular method employed for purposes of achieving monomer grafting to the keratin fiber it is nevertheless found, other attendant advantages notwithstanding that the beneficial effects are often vitiated due to markedly suboptimum strength properties and particularly wet strength properties in the keratin product, i.e., reference being made in this regard to tensile strength. The importance of the latter is largely self-evident and becomes manifestly clear when considered in connection with the treatment of garments designed for personal wear. As will be recognized, even minor departures from optimum strength characteristics with such fabrics may suffice to vitiate any practical advantage which might otherwise be obtainable. Clearly, and especially with respect to garments designed for external wear, the matter of tensile strength is of vital importance bearing upon the appearance, useful life etc. of the garment. Considerations associated with structural integrity are likewise of primary importance in connection with techniques specifically adapted to enable the modification of hair whether of human origin or otherwise; accordingly, in the absence of the requisite degree of tensile strength, the final hair product will inevitably exhibit an untoward resistance to form manipulation e.g., bending, as well as minimal form retention stability with the consequent tendency to snag, snap, tear, etc. or otherwise result in an aesthetically displeasing appearance. The foregoing desiderata are, of course, highly inimical to expeditious hair management. In an effort to overcome or otherwise mitigate the foregoing and related disadvantages, considerable industrial activity has centered around the research and development of keratin modification techniques capable of providing a keratin product modified as desired and yet possessed of optimum strength characteristics and particularly tensile strength. Although much in the way of meritorious improvement has characterized such efforts, the overall improvement proves in most instances to be of marginal significance only. Thus, it is usually found in practice that the amelioration of problems associated with structural stability and integrity often leads to deleterious effects upon one or more of the other essential properties desired in the treated keratin material product. In addition, economic considerations alone may well be of such significance as to recommend against a given method thus necessitating resort to less costly albeit inferior techniques.

In accordance with the discovery forming the basis of the present invention, it has been ascertained that processing singularly and beneficially adapted for use in the treatment of keratinous substrates and involving the use of vinyl monomer capable of free radical-induced polymerization may be synergistically modified to advantage and thereby rendered more effective by the employment of a posttreating operation involving the subjection of the treated keratin substrate to a substance selected from a highly delimited class of materials, the latter serving to augment or otherwise enhance the structural integrity and particularly tensile strength of the treated substrate.

Thus, the primary object of the invention resides in the provision of an improved process for the treatment of keratinous substrates wherein the aforementioned difficulties and disadvantages are eliminated or at least mitigated to a substantial extent.

A further object of the present invention resides in the provision of a process for the treatment of modified keratinous substrates which makes possible the production of a final keratin product having exceptional structural integrity said process being effectively devoid of any tendency to disrupt or otherwise adversely affect the properties desired in the final keratin material selected for treatment.

A still further object of the present invention resides in the provision of a process for the posttreatment of modified keratin substrates said process having exceptional utility in connection with the treatment of modified fibrous materials constituted wholly or partly of keratin whereby to render same more resistant to adverse environmental effects such as moisture, heat, and the like.

Other objects and advantages of the present invention will become more apparent hereinafter as the description proceeds.

The attainment of the foregoing and related objects is made possible in accordance with the present invention which in its broader aspects includes the provision of a process for the modification of monomer pretreated keratinous substrates which comprises treating said substrate with an aqueous solution containing a small but effective amount of copper ammonium hydroxide. Otherwise stated, the process of the present invention comprises treating a keratinous substrate, the latter having been previously treated with a monomer solution under free radical induced-polymerization conditions with said copper ammonium hydroxide solution.

The posttreatment operation prescribed for use in accordance with the present invention is most efficaciously implemented subsequent to completion of the keratinous substrate monomer treatment. As will be appreciated, the results contemplated herein in nowise depend critically upon the particular point of time at which such posttreatment operation is effected; accordingly, copper ammonium hydroxide solution treatment may be carried out immediately subsequent to monomer treatment or some period thereafter.

The concentration of copper ammonium hydroxide in the aqueous solution is largely a matter of choice the salient requirement imposed in this regard being that such concentration be tantamount to effective" quantities i.e., quantities conducive to the obtention of the desired degree of structural integrity. Thus, the particular proportions employed may range from a small but effective amount e.g., a 0.01 molar solution to concentrations approximating the solubility limit. The upper limiting concentration value of copper ammonium hydroxide may vary within a relatively wide range and thus nothing critical resides in the selection thereof. Thus. a point will be reached where further increase in copper ammonium hydroxide concentration fails to provide commensurate increase in structural modification and thus a levelling" effect is achieved. This willdepend of course on the total quantity of polymer present in the keratin mass as well as the population density of function groups. In any event, solution concentrations on the order of at least 0.01 M are found to provide optimum advantage for the vast majority of applications.

It is likewise recommended to employ the copper ammonium hydroxide solution in amounts sufficient to yield, on a weight basis, having reference to total keratin treated, a value within the range of from about 3:1 to about 20:1. Again, the sole requirement imposed in this regard is that the solution be used in effective quantities, the quoted term having the sig nificance previously assigned. As indicated, the selection of an upper limiting concentration value will be determined in large part by economic considerations, levelling" effects and the like.

In some instances it may be desirable to avoid the use of more concentrated solutions; when so proceeding, it is advisable to limit the copper ammonium hydroxide concentration to the lower ranges and merely repeat if necessary, contacting of such solution with the keratin material e.g., with successive, replenished solutions. In those circumstances permitting the use of more concentrated solutions, the requisite quantity of copper ammonium hydroxide may be introduced by the use of a single solution thereby obviating any necessity for the use of plural solution treatments, the latter proving rather burdensome from a materials-handling standpoint. Copper ammonium hydroxide keratin contacting in accordance with the present invention is carried out in alkaline media the efficacy of the copper treatment having been discovered to depend critically thereupon. Investigation indicates the locus of optimum advantage to obtain for a pH range of about 7.5 to about 1 1.0 with a range of 8.5 to 9.5 being particularly preferred. Among the factors found to exert a significant influence upon the efficacy of the pH selected is the matter of duration or interval of copper solution-keratin contacting. Thus, within certain limits to be more fully delineated hereinafter, it has been determined that more prolonged contacting periods are most advantageously utilized at the lower pH ranges; otherwise stated, increasing the pH enables the use of reduced contacting intervals without in any wise detracting from the effectiveness of the posttreatment operation. In fact, the results obtained illustrate quite unequivocally that reduced contacting periods at higher pH actually lead to more marked improvement in the wet strength characteristics of the keratin substrate.

Duration of copper ammonium hydroxide keratin fiber contacting should likewise be selected having reference for example to the amount of polymer present in the keratin substrate, the overall efficiency of solution-keratin contacting, the concentration of copper ammonium hydroxide in the treating solution, the penetrability or porosity of the keratin mass, temperature etc. Thus, periods ranging from as little as 1-2 minutes to 4-6 hours may be feasible in a given situation. However, elevated temperature ranges are in no way necessa ry or for that matter particularly recommended; thus, the copper ammonium hydroxide solution treatment may be efficaciously implemented at room temperature. The actual period of contacting will likewise depend of course upon the extent of keratin modification desired; in some instances, only partial restoration of wet strength characteristics may be desired and thus, the solution contacting period can be adjusted accordingly.

In actual practice the fiber to be treated may be immersed in the aqueous solution of copper ammonium hydroxide for the desired interval under conditions favorable to uniform contacting of the copper compound with the entire keratin mass. Alternatively, the copper solution may be applied directly to the keratin mass as by spraying, mechanical applicator etc. this procedure being particularly feasible in those instances wherein the keratin fiber is to be differentially treated i.e., only certain, predetermined areas. In view of toxicity problems, the processing of the present invention is primarily intended for use in connection with the treatment of materials constituted wholly or partly of keratin such as offscalp i.e., nonliving human hair such as would be present in wigs and other forms of headdress, woolen garments and the like. By virtue of such processing, the specific material subjected thereto is characterized by markedly superior physical properties for example, garment wearability, resistance to humid environments and the like, while headdress articles so treated are possessed of greatly improved form stability e.g., curl retention stability, ease of manageability and manipulation etc.

The keratin material contemplated for treatment in accordance with the present invention are those containing polymer fragments derived from monomer materials having at least one functional group capable of acting as an electron donor in the formation of coordination complexes e.g., with the copper ammonium hydroxide. Specific representatives of such functional groups include without necessary limitation, hydroxyl, carboxyl, nitrile, imide, amide, tertiary amine, carbalkoxy i.e., ester groups etc. As indicated, the mer units comprising the recurring moiety of the polymer fragment may be polyfunctional and thus contain more than one functional group. when present on adjacent carbons i.e., alpha-positioned functional groups, the improvements and advantages made possible by the present invention are even more markedly manifest apparently due to chelating effects. Keratin substrates found to be particularly beneficial for use in the practice of the present invention include those containing polymer fragments derived from the following monomer materials:

acrylonitrile ethylene glycol mono methacrylate acrylic acid methacrylic acid 2-dimethylamino ethyl methacrylate glycidyl methacrylate vinyl pyridine methyl methacrylate methyl acrylate ethyl acrylate butyl acrylate allyl acrylate butyl methacrylate isobutyl methacrylate t-butyl methacrylate allyl methacrylate 3,4-butenyl acrylate 2-hydroxypropyl methacrylate 3-hydroxypropyl methacrylate 2,4-dihydroxybutyl methacrylate acrylamide N,N-diethyl-methacrylamide N,N-dipropyl acrylamide N,N-ethylene-bis-(N,N-diethyl)acrylamide N,N '-propylene-bis-(N,N-diisopropyl) methacrylamide As will be appreciated, in those instances wherein the keratin substrate has been treated with monomeric materials of the polyfunctional type e.g., those materials containing more than one vinyl-type grouping such as, allyl methacrylate, divinyl benezene and the like, considerable polymer crosslinking may occur in addition to the predominant graft copolymerization action as a result of the polymerization-inducing oxidation treatment. This result obtains of course since monomers of this nature possess more than one group capable of undergoing polymerization under the reaction conditions employed. It will be understood that the present invention contemplates the treatment of keratin substrates containing polymer fragments derived from admixtures comprising two or more monomer components. In such instances, it is only required that at least one of the monomer materials possess at least one coordination complex forming group of the type hereinbefore defined, such monomer comprising at least of the monomer admixture. No such requirement is imposed as regards the nature of the other monomeric components of the admixture i.e., such materials may be completely devoid of functional groups of the type hereinbefore described.

Processing in accordance with the present invention is found to be particularly beneficial when the prescribed keratin posttreatment operation is effected with keratin substrates having been subjected to the monomer treatment operation described in copending applications, Ser. Nos. 829,095, 829,096 and 829,097, i.e., in the presence of free radical liberating catalyst or initiator. Catalyst materials suitable for such use and described in such aforereferenced copending applications include, without necessary limitation, cumene hydroperoxide, hydrogen peroxide, benzoyl peroxide, acetyl peroxide, tertiary butyl hydroperoxide, alkali metal salts of peroxides, alkali metal and ammonium salts of peracids such as peracetic acid, perbenzoic acid, per-sulfuric acid etc. According to the procedure described in copending application, Ser. No. 829,097, particularly beneficial results as regards rate of monomer takeup are obtainable with the use of organosoluble initiator compounds such as typified by cumene hydroperoxide. In any event, selection of a given catalyst system will depend, inter alia, upon the solubility characteristics of the monomer involved, solvent system employed etc. Thus, the catalyst material or organosolubility depending upon the factors mentioned.

In any event, it is of utmost importance to note at this juncture that the particular means employed for introducing the monomer substance into the keratin substrate in the form of polymerized monomer fragments is of secondary importance since the present invention may be exploited to advantage in connection with the treatment of keratinous substrates containing polymerized products having function groups possessing electrons capable of being donated to an acceptor cation i.e., copper. The procedures delineated in copending applications Ser. Nos. 829,095, 829,096 and 829,097 warrant particular mention herein in view of their outstanding capacity to provide a keratin substrate possessed of optimum properties in a wide variety of aspects. However, such reference should not be interpreted as being tantamount to limitation thereto. Indeed, the contrary situation obtains since the effica' cy of the subject invention extends to monomer-treated keratin substrates characterized as defined as regards polymer content regardless of the particular means availed upon whereby to accomplish such monomer pretreatment.

The process described herein may be effectively applied to a relatively wide variety of keratinous materials including for example various types of hair e.g., camel hair, mohair, horse hair, cattle hair, off-scalp human hair etc., fabric materials constituted wholly or partly of wool and the like. As is well known, keratin materials are categorized among the proteins containing varying quantities of chemically combined sulfur the latter being present in the protein molecule in the form of disulfide groups also referred to as cystine linkages. Thus, the amino acids are linked through amino groups to form long chain structures known as polypeptides the latter in turn being mutually interconnected through disulfide linkages. Thus, according to the procedures described in copending applications, Ser. Nos. 829,095, 829,096 and 829,097 the disulfide linkages i.e., S--S bonds are converted into thiol groups attached to polypeptide chains, interreaction of the peroxide initiator and the thus-formed thiol groups culminating in the formation of free radical species the latter serving as the polymerization initiating agency.

The following examples are given for purposes of illustration only and are not to be considered as necessarily constituting a limitation on the present invention. In the examples, all parts and percentages given are by weight unless otherwise indicated.

in the following examples the keratin substrate employed, where human hair, is from brown caucasian human hair (nonliving) and where wool, 64's Merino dry combed top wool. The polymer material is introduced into the keratin substrate in the following manner. Single fibers, hair or wool, are immersed in a 6 percent ammonium thioglycolate solution (pl-l 9) for about 3 minutes, washed in deionized water and then immersed in a water-alcohol mixture of vinyl monomer (10 percent) and cumene hydroperoxide (4 percent) for 60 minutes at room temperature. Sufficient alcohol is added to the system to completely solublize the hydroperoxide and monomer ingredients. The amount of polymer introduced into the fiber is calculated by weight pickup as determined in a dry box. The posttreatment operation is carried out by immersing the thus-treated fiber in a solution of copper ammonium hydroxide having the concentration specified for the time period indicated.

EXAMPLE 1 In this example the keratin fiber selected for treatment comprises human hair containing 21 percent by weight polyethylene glycol monomethacrylate. Stress-strain properties are determined with respect to the polymer-containing hair fiber both prior to (calibration) and following copper ammonium hydroxide treatment in order to enable a comparative evaluation of the resultant wet strength properties. Calibration is carried out by placing the hair sample on a cellulose acetate tab and immersing same in deionized water at room temperature for a period of l to 2 hours. Thereafter, the hair fiber specimen is stretched to 20 percent of its original length on an lnstron tensile tester at a rate of extension of 0.2 inches per minute. The fiber is then relaxed in water for 1 hour, dried, cut from the tab and weighed. The postrelaxation step serves to completely restore the strength properties of the hair sample to the original, prestretching values. The hair fiber is then immersed in an aqueous solution of copper ammonium hydroxide (2 percent) having a pH between 10 and 10.5 for a period of i5 minutes. The hair sample is thereupon stretched again in the lnstron tester in the manner described. The changes in wet strength properties are calculated by comparison of the data obtained from the calibration and copper ammonium hydroxide treatments, Positive percentage values signify increases in the corresponding property.

% Change Ex. No. We HL 5 2 +9.5 no.2

Again, substantial restoration of the wet strength properties 1 O of the hair fiber sample is achieved despite a contacting period of only l5 minutes.

When the procedures of examples I and 2 are repeated but wherein the period of contacting the keratin fiber and copper ammonium hydroxide is increased to 30 minutes, similar im- 1 s provement in the wet strength parameters is obtained.

EXAMPLES 3-6 Example 2 is repeated except that the period of contacting the hair fiber samples and the copper ammonium hydroxide 20 solution (0.25 M) is varied as indicated in table 1.

TABLE 1 Time of 25 reaction Percent Percent Percent Example number (minutes) We HL F i 1 Force to 20% extension.

As the foregoing results make manifestly clear, for a given pH, increased contacting periods up to around 30 minutes tend to provide greater net increases in wet strength properties. However, and as previously pointed out, when operating within the lower pH ranges, the realization of optimum results usually requires the use of correspondingly enhanced contacting periods. This aspect will be illustrated by the following examples.

EXAMPLES 7-l0 The procedure of example l is repeated except that the pH of the copper ammonium hydroxide solution as well as the contacting period of such solution with the hair fiber sample is varied to the values summarized in the following table.

% Change TABLE 2 Ex. No. We HL Percent I +323 Example number pH 30 min. min. 90 min. 120 min 0. 34 -1. 75 -0. 46 +6. 50 l -1. 06 +2. 14 +6. 56 +7. 76 wherein We represents work to 20 percent extension and HL +7.00 -+5. 01 +2.80 +5.48 +10. 74 +1.26 +3.99 +3.77

represents HOOKEAN limit.

As the foregoing data make manifestly clear, significant increases in wet strength properties of the hairfiber sample are achieved despite the use of relatively minor quantities of copper ammonium hydroxide and for a contacting period of but 15 minutes. At this point it should be mentioned. that an 18 percent increase in a given property corresponds to total restoration of the original wet strength parameters. The net change in properties using as a basis the natural or untreated i.e., nonmonomer treated fiber can be derived by the following empirical equation X==0.859Y-l5.7 wherein X represents the total change from the grafted state and Y the total change from the untreated state. The above reported values represent of course changes from the grafted state.

EXAMPLE 2 Example 1 is repeated except that the hair fiber sample employed contains 19.8 percent by weight of polymethacrylic acid. The results obtained are as follows:

Thus, when operating at a pH of 7.5, contacting periods on the order of 2 hours prove necessary in order to achieve an appreciable measure of strength-property restoration. However, the converse situation obtains at higher pH values i.e., on the order of at least 8 to 8.5 wherein significant reductions in contacting period are found to provide greater structural enhancement as compared with the more prolonged contacting prolonged By comparison, a further run carried out utilizing an identical polymethacrylic acid containing hair fiber but wherein the pH of the copper ammonium hydroxide solution has a value of 7.0 failed to provide even marginal improvement in the wet strength properties of the hair fiber despite protracted solution treatment intervals. Results similar to those described in connection with examples 1-10 are obtained when the processing described therein is repeated but employing as the keratin material polymethacrylic acid grafted wool and polyethylene glycol monomethacrylate grafted wool i.e., manifold improvement in wet strength properties is obtained, such structural improvement being manifested in the form of superior wearability toughness as well as appearance.

The processing described herein is advantageously adapted for implementation with respect to keratin materials containing polymer fragments derived from a wide variety of monomer material the sole condition imposed being that the monomer material employed, or, in the case of monomer mixtures, at least 10 percent of the said mixture on a molar basis, contain at least one functional group capable of forming a coordination complex with the copper compound. Thus, similar improvement in wet strength properties is obtained when the exemplified procedures are repeated but employing wool and hair fibers containing polymer fragments derived from the foregoing monomer materials:

methyl methacrylate isobutyl methacrylate 3,4-epoxybutyl methacrylate Z-hydroxypropyl methacrylate 2,4-dihydroxybutyl methacrylate methacrylamide 4-vinyl pyridine N,Ndipropylacrylamide N,N'-ethylene-bis-(N,N-diethyl) acrylamide allyl methacrylate In each case, substantial improvement in wet strength properties is obtained. However, when employing acrylic type monomers, it is usually advisable to employ more highly concentrated copper ammonium hydroxide solution such a procedure being found advisable in view of the somewhat inferior tendency of ester groups to coordinate with the copper compound.

What is claimed is:

1. In a process wherein a keratin substrate is polymerized with a vinyl monomer having at least one functional group capable of acting as an electron donor group in the formation of coordination complexes, under free radical inducted polymerization conditions, the improvement which comprises posttreating said modified substrate with a small but effective amount of an aqueous copper ammonium hydroxide solution, said treatment being carried out at an alkaline pH.

2. A process according to claim 1 wherein said alkaline Ph is within the range of about 7.5 to about 1 1.0.

3. A process according to claim 1 wherein said keratin substrate comprises off-scalp human hair.

4. A process according to claim 1 wherein said keratin substrate comprises wool.

5. A process according to claim 1 wherein said monomer comprises ethylene glycol monomethacrylate.

6. A process according to claim 1 wherein said monomer comprises methacrylic acid.

7. A process according to claim 1 wherein said monomer comprises acrylonitrile.

8. A process according to claim 1 wherein said monomer comprises methyl methacrylate.

9. A process according to claim 1 wherein said monomer comprises acrylic acid.

10. A process according to claim 1 wherein said monomer comprises dimethylaminoethyl methacrylate.

11. A product produced in accordance with claim I. 

2. A process according to claim 1 wherein said alkaline Ph is within the range of about 7.5 to about 11.0.
 3. A process according to claim 1 wherein said keratin substrate comprises off-scalp human hair.
 4. A process according to claim 1 wherein said keratin substrate comprises wool.
 5. A process according to claim 1 wherein said monomer comprises ethylene glycol monomethacrylate.
 6. A process according to claim 1 wherein said monomer comprises methacrylic acid.
 7. A process according to claim 1 wherein said monomer comprises acrylonitrile.
 8. A process according to claim 1 wherein said monomer comprises methyl methacrylate.
 9. A process according to claim 1 wherein said monomer comprises acrylic acid.
 10. A process according to claim 1 wherein said monomer comprises dimethylaminoethyl methacrylate.
 11. A product produced in accordance with claim
 1. 